Don't know if these were the 'best', but they are memorable to me from playing my first PC games as I'm sure a lot of these games people are posting. This is pretty much the games of Star Wars post since LucasArts' games were my jam back then.
Finding out that you play as Keyan Farlander in that game, the only surviving Y-Wing pilot from the first Death Star attack was mind blowing to me back then
Even more of a surprise to play as an Imperial, Maarek Stele, and seeing Thrawn in an actual game. This video shows the differences in the actual intro of the game between 3 versions.
Star Wars X-Wing Alliance
The last great Star Wars space sim, the intro gives me chills still - awesome action & muisc, great CGI
Dark Forces 1
Finding out who stole the Death Star plans and playing as him
Dark Forces 2
Dark Forces II, seeing live-acting and more expanded universe stuff was awesome when I was younger, LucasArts came through for many that wanted
more Star Wars.
Other ones:
Rebellion
Rogue Squadron
Shadows of The Empire
Knights of The Old Republic
Rebel Assault 2
It's been 3 years since the new Era of Star Wars, and there are has not been anything like these with such a wide variety of genre game types.